The present invention relates to a seat switch for use in a vehicle and, more particularly, the present invention relates to a seat switch that senses the presence of an operator in a vehicle.
It is common in the prior art to equip a vehicle with a seat switch that allows the operator""s presence on the seat to be monitored. If the vehicle is running and the operator steps off the vehicle, there is a danger that the operator will be seriously injured. To reduce the hazard of such serious accidents, electrical circuits are used to disable the engine if the operator steps or falls from the vehicle. One example of such a circuit is found in U.S. Pat. No. 5,190,019 to Harvey, which issued on Mar. 2, 1993. The ""019 Harvey patent is assigned to the assignee of the present invention. The ""019 Harvey patent discloses a seat switch that in combination with other switches forms a circuit that disables a magneto energized spark plug on a lawn or garden tractor to shut down an engine. The disclosure of the Harvey patent is incorporated herein by reference.
U.S. Pat. Nos. 4,795,865; 5,424,502 and 5,548,888, assigned to the assignee of the present invention, concern operator presence sensing on a vehicle having a seat. U.S. Pat. Nos. 4,795,865; 5,424,502 and 5,548,888 are incorporated herein by reference.
Hall effect devices in conjunction with magnets have been used in the past to detect the presence of an operator in a seat. For example, U.S. Pat. No. 5,481,078 shows a hall effect operator presence system for an operator seat that provides a signal to indicate when the seat is occupied. The operator""s presence is sensed by permitting seat rails to pivot about a pivot point against leaf springs designed to support the operator""s weight (plus a known factor of an operator""s weight) so that the rear of the seat is raised when the seat is unoccupied. When an operator occupies the seat, the spring deflects and the rear of the seat moves down, resting on the seat support pan. An electronic sensor detects the seat position to provide a, position signal.
U.S. Pat. No. 5,565,829 shows a Hall device used in conjunction with a magnet to monitor the presence of an operator in a seat. A hall effect sensor is mounted in a housing. The housing containing the hall effect sensor is mounted either to a base plate or a seat. A magnet is mounted to the other of the base plate or the seat. When an operator sits in the seat either the Hall effect sensor or the magnet is moved to cause the Hall effect sensor to generate a signal that indicates that an operator is present in the seat.
The present invention concerns a seat switch for controlling operation of a vehicle engine. The seat switch includes a switch frame, a magnet, a Hall effect sensor and a vane. The switch frame is adapted to be connected to the vehicle seat. The magnet, having an associated magnetic field, is mounted in the switch frame. The Hall effect sensor is mounted in the switch frame spaced apart from the magnet. The vane is movably connected to the switch frame and moves in response to an operator sitting on the vehicle seat. The vane moves from a first position that allows a magnetic field to be sensed by the Hall effect sensor to a second position that prevents the magnetic field from being sensed by the Hall effect sensor. When the vane is in one of the first or second positions a signal from the Hall effect sensor inhibits the vehicle engine from running. In one embodiment, if the operator leaves his or her seat, the seat switch deactivates the engine by allowing a magnetic field from the magnet to reach the Hall device by removing the vane from between the magnet and the Hall device. The Hall device produces an output signal that indicates that the operator is not in the vehicle seat and the engine is prevented from running.
A Hall effect seat switch constructed in accordance with the present invention is reliable and long lasting. The Hall effect seat switch does not include contacts that wear over time as they are engaged and disengaged. The Hall effect seat switch is adapted to be used on a wide array of vehicle seats, without requiring extensive modifications to the seat. The Hall effect seat switch of the present invention is especially well adapted for use on lawn and garden vehicles, such as riding lawn mowers. Because the design of the Hall effect seat switch allows it to be used on any vehicle seat, without requiring a great deal of modification to the seat, the Hall effect seat switch is also well suited for use on construction and agricultural vehicles.
Additional features of the invention will become apparent and a fuller understanding obtained by reading the following detailed description in connection with the accompanying drawings.